Detection and identification of explosives are important in forensic, security screening, environmental pollution and a variety of other applications. A variety of analytical tools and methods, including mass-spectrometry, gas chromatography and ion mobility spectrometry, are used in the laboratory for detection and identification of explosives. These methods have also been applied in airport security screening systems. Since conventional X-Ray and CT systems are not analytic systems, complementary analytical methods are used to verify suspected explosives that are detected. Systems based on these methods perform detection or identification utilizing material sampling. Conventional sampling methods include vapor detection systems, such as sniffers, which use vacuum pumping, and pad swiping systems, which detect traces of contaminants on a body surface. However, even the most sensitive methods are limited by sampling, since the system can fail to detect an explosive because the sampling is not done efficiently enough.
Explosive detection methods and systems are described, inter-alia, in “Forensic and Environmental Detection of Explosives”, Jehuda Yinon, John Wiley & Sons Ltd. (1999); and in a review by Jeffrey I. Steinfeld and Jody Wormhoudt, Ann. Rev. Phys. Chem. (1998), v49, 203–232. Steinfeld and Wormhoudt mention the stickiness of explosive particulates as an important physical-chemical property. This property of explosive particulates enables traces of explosives to be detected on materials that have come in contact with explosives.
A method for detection of traces of explosives is described by Haley et al in U.S. Pat. No. 5,760,895. This patent describes performing detection without sampling by applying laser radiation, causing micro-denotation of explosive particulates that are found on a suitcase surface. The explosive is detected by measuring the characteristic emission of the explosive micro-detonation. Another method, described by Funsten et al in U.S. Pat. Nos. 5,638,166 and 5,912,466, uses sampling to detect micro-detonation emission caused by heating resulting in deflagration.
The following U.S. Patents and articles are believed to be representative of the prior art: U.S. Pat. Nos. 6,160,255; 5,912,466; 5,906,946; 5,826,214; 5,760,895; 5,728,584; 5,697,373 and 5,638,166.
Arusi-Parpar et al Applied Optics, 2001 V40, No. 336, pp 6677–6681;
G. Mizutani et al, J. of Luminescence, 2000, 87–89, pp 824–826;
L. Smilowitz et al, Abstracts, June, 2001 SHOCK 01, Session L2-DE;
C. Cheng et al, J. of Forensic Sciences, 1995, 40 pp 31–37;
K. Horton et al, Abstracts, Lunar and Planetary Science XXXII (2001).